The use of DiscretizationMethod=Clusters can cause a process error that is not so clear:
Internal error: Unexpected error. File ‘mddiscretizer.cpp’, row 1532, function ‘MDDiscretizer::GetBucketForValue’.
This happens because you have an attribute with few distinct values to do a discretization in required clusters. To workaround the problem you can disable discretization of the incriminated attribute (you could have only one in the dimension, otherwise some SELECT COUNT( DISTINCT fieldname ) FROM Dimension could help you in the search).
Even if it would be preferable to process the dimension with a smaller number of clusters without blocking errors, it would be necessary at least to have a better error message that indicate the problem in discretization.
The problem affects both SSAS RTM and SSAS SP1. I already filed a bug in MSDN Product Feedback Center, but blogging it could help other unlucky developers.